The National Institute of Child Health and Human Development, NICHD, the Epidemiology Branch intends to assess the impact of infertility treatment, including but not limited to ovulation induction and assisted reproductive technologies, ART, on three domains of children's health-growth, motor and social development, from birth through three years of age for a geographically and temporally defined birth cohort of children. Developmental status of children is broadly defined to include major and minor neurodevelopment;impairment and physical growth patterns and proportionality (weight-for height).